Your Instagram needs to be a Professional account to connect to Scaled Creator, and either a Creator or Business account works. Here's how to switch your Instagram to a Professional account.
Go to your Accounts page.
Click the Instagram icon.
Choose Connect Instagram directly or Connect through Facebook, then log in.
Which option to choose
Connect through Facebook is the recommended option and unlocks all features, including Button DMs. It uses your Facebook login, so your Instagram has to be linked to your Facebook Page first. Here's how to link your Instagram to your Facebook Page. Connect Instagram directly uses your Instagram login instead.
To compare the two DM formats, see Button DMs vs Link DMs.
After you connect
Turn on message access in Instagram so your automated DMs can send. Go to Settings, then Messages and Story Replies, then Message Requests, and make sure Allow Access to Messages is on. Here's a quick walkthrough for turning on message access.
A private or incognito browser window helps avoid conflicts from saved Facebook and Instagram logins. If Instagram won't connect, see My Instagram Is Not Connecting.